Noticed this bug when I was playing Militia, but after that also noticed it on the Russian and Insurgent team. Somehow after reloading the mag on the PKM will disappear. Unlike the invisible RPG bug I think this one is caused by starting the reloading process then going prone, or at least that's the pattern I noticed in-game, also happens if you use 1 or 2 pkm mags then reload on an ammo bag.
screen12 - Servimg.com - Free image hosting service
If you notice you can see the hand that should be open is clearly visible, and if I remember right the screen shot was taken with the PKM undeployed because I was running around with it.
Graphics setting as they may be important: all set to medium, anti-aligning on 2x, and effects setting on high
Graphics card: XFX 2GB
Map: in screenshot it was Iron Ridge (AAS 64), also saw it on Vadso City (AAS 64), Kokan (INS 64), and Fallujah (INS 64) all on CIA Hookers and Kokan
screen12 - Servimg.com - Free image hosting service
If you notice you can see the hand that should be open is clearly visible, and if I remember right the screen shot was taken with the PKM undeployed because I was running around with it.
Graphics setting as they may be important: all set to medium, anti-aligning on 2x, and effects setting on high
Graphics card: XFX 2GB
Map: in screenshot it was Iron Ridge (AAS 64), also saw it on Vadso City (AAS 64), Kokan (INS 64), and Fallujah (INS 64) all on CIA Hookers and Kokan